1. Field of the Invention
The present invention relates to a technique for detecting a face region of a person from image data, and executing personal authentication.
2. Description of the Related Art
Conventionally, a technique for executing personal authentication using a face detection function is known. This technique extracts feature data of a face region different for each person from detected face image data, and compares the feature data with those which are registered in advance, thereby identifying whether or not the detected face is that of a registered person.
However, since the feature data are influenced by the facial expression of the face region, the difference between the facial expression of the face region and that upon registration deteriorates the precision of personal authentication.
In order to avoid this, a method of detecting the facial expression of a face region, determining whether or not the detected facial expression is valid to execute personal authentication, and executing the personal authentication using new image data when it is determined that the facial expression is invalid is known (for example, see Japanese Patent Laid-Open No. 06-119433).
However, with the method described in Japanese Patent Laid-Open No. 06-119433, since the personal authentication cannot be started until a valid facial expression is obtained, it takes much time until authentication. Also, when a valid facial expression does not appear, the authentication is disabled.